Systematics and life habit in Serpula israelitica Amoureux, 1977 (Polychaeta Serpulidae) from the Mediterranean with remarks on other soft-bottom serpulids

Abstract

A redescription of the poorly known species Serpula israelitica Amoureux, 1977 from the central Mediterranean is given, using both traditional and new systematic characters. Morphological traits are compared and contrasted with other Mediterranean Serpula species to understand their interrelationships. The distribution, ecology and life history of S. israelitica are also discussed. The species belongs to a unique group of serpulids that settle not on hard substrates but on sandy to muddy bottoms from shelf to upper slope, where they exhibit a free-living habit. Mainly empty tubes are found, most of which are detached anterior/distal parts, occasionally closed off at their posterior/proximal damaged end by a mineralized tabula, a transverse internal tube structure ensuring protection to the animal inside its broken tube. Hypotheses on different functional adaptations to counteract sinking in other soft-bottom serpulids are given.

Keywords:

• tube worms
• tube morphology
• systematics
• soft-bottom dwellers
• Mediterranean

Acknowledgements

G.V. Helgason and G. Gudmundurson (Marine Invertebrate Icelandic Institute and Museum of Natural History, Reykjavik) made the BIOICE material available. H. ten Hove (Zoological Museum, University of Amsterdam) kindly shared personal observations on some systematic characters. A. Viola (Dipartimento di Scienze Geologiche, Sezione di Oceanologia e Paleoecologia, Catania University) supplied SEM assistance. M. Viccaro (Department of Geological Science, Mineralogy, Petrography, Volcanology and Geochemistry section, Catania University) assisted in microanalyses. M.N. Ben-Eliahu (The Hebrew University of Jerusalem, Biological Collections, Section of Aquatic Invertebrates) and O. Vinn (Institute of Geology, University of Tartu) kindly exchanged data. H. ten Hove (Zoological Museum, University of Amsterdam), T.A. Macdonald (Department of Biological Sciences, Univeristy of Alberta, Edmonton) and a third anonymous journal referee performed detailed and helpful reviews of the manuscript. H. Zibrowius (Station Marine d'Endoume, Marseille) and A. Rosso (Department of Geological Science, Oceanology and Palaeoecology section, Catania University) provided constructive comments. This paper was supported by PRA grants (Rosso), Catania University. It represents Catania Palaeoecological Research Group: contribution no. 354.